Operando monitoring of Supported Ionic Liquid Phase (SILP) catalysts by microwave-based methods exemplarily investigated for the water gas shift reaction

固定化离子液体（IL）是用于催化的有吸引力的材料，例如，对于负载离子液相（SILP）概念，其中含有均相催化剂的IL固定在固体载体上。应用集中在水煤气变换（WGS）反应。对于具有Ru-SILP催化剂的WGS，已经证明了载体的孔填充度和IL中的催化剂浓度对有效活性的影响，但仅不完全理解。通常，均相催化剂的稳定性取决于进料气体。因此，通过用H2还原金属络合物观察到Ru纳米颗粒形成。在技术过程中，催化剂失活通常仅通过测量活性的降低来观察。只有对催化剂的后续研究（表面、组成等）可以推断出可能的原因。在设想的项目中，将首次在工艺条件下研究用于WGS反应的SILP催化剂的基于非接触式射频（RF）的操作状态监测。选择WGS反应是因为它的重要性（例如NH3合成），并且因为我们已经获得了SILP系统的良好经验。初步研究表明，RF方法可以用于诊断SILP催化剂的状态。因此，总体目标是确定非接触式RF方法是否以及在多大程度上适用于连续过程监测。计划的研究基于三个支柱：1）Jess小组关于WGS与SILP反应的初步工作，2）Moos小组关于废气催化剂基于RF的状态监测的经验，以及3）关于SILP气体干燥系统基于RF的水负载检测的联合工作。在该项目中，包含IL和催化剂的载体的介电材料性质将被系统地研究作为IL的孔填充度和催化剂负载的函数。温度的影响也要考虑在内。还应该澄清纯IL的介电性质与SILP的介电性质有多大不同以及催化材料对介电材料性质的影响有多大。伴随的WGS反应的动力学研究是必不可少的。RF方法最终将用于建立催化“性能”降低与RF共振参数变化之间的关系。这将用于监控SILP催化剂的运行。还设想了化学反应过程及其对介电材料参数的相互作用的建模。这种联系将允许在反应室中的过程被理解和定量描述的空间和时间分辨率从测量的RF数据。

Immobilized ionic liquids (ILs) are attractive materials for catalysis, e.g., for the Supported Ionic Liquid Phase (SILP) concept, where the IL that contains a homogeneous catalyst is immobilized on a solid support. The application focuses on the water gas shift (WGS) reaction. For WGS with a Ru-SILP catalyst, the influence of the pore filling degree of the support and the catalyst concentration in the IL on the effective activity has been demonstrated, but is only incompletely understood. Often, the stability of the homogeneous catalyst depends on the feed gas. Thus, Ru nanoparticle formation was observed by the reduction of the metal complex with H2. In technical processes, catalyst deactivation is often observed only by measuring the decrease in activity. Only subsequent investigations of the catalyst (surface, composition, etc.) allow to deduce possible reasons for this. In the envisaged project, the contactless radio frequency (RF)-based operando state monitoring of SILP catalysts for the WGS reaction will be investigated for the first time under process conditions. The WGS reaction was selected, because of its significance (e.g. NH3 synthesis) and because we have already gained good experience with SILP systems. Preliminary studies show that the RF method can be used to diagnose the state of the SILP catalyst. The overall objective is therefore to determine whether and to what extent the non-contact RF method is suitable for continuous process monitoring. The planned investigations base on three pillars: 1) on the preliminary work of the Jess group on the WGS reaction with SILP, 2) on the experience of the Moos group on RF-based state monitoring of exhaust gas catalysts, and 3) on joint work on RF-based water loading detection of SILP gas drying systems. In the project, the dielectric material properties of the support that contains the IL and the catalyst are to be systematically investigated as a function of the pore filling degree and the catalyst loading of the IL. The influence of temperature is also to be taken into account. It should also be clarified how much the dielectric properties of the pure IL differ from those of the SILP and how much the catalytic material influences the dielectric material properties. Accompanying kinetic studies of the WGS reaction are essential. The RF method will eventually be used to establish a relationship between the decrease in catalytic "performance" and changes in RF resonance parameters. This will be used to monitor the SILP catalyst operando. Modeling of the chemical reaction processes and their interactions on the dielectric material parameters is also envisioned. This linkage would allow the processes in the reaction chamber to be understood and quantitatively described with spatial and temporal resolution from the measured RF data.